| Geology of the County | ||
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In Larue County, water is obtained from consolidated sedimentary rocks of Silurian, Devonian and Mississippian ages, and from unconsolidated sediments of Quaternary age. Geologists call the oldest rocks found at the surface in Larue County the Brassfield Dolomite. This formation is from the Silurian, which was deposited in warm seas 430 million years ago. Above the Silurian rocks is the Devonian New Albany shale, formed 400 million years ago when the deep sea floor became covered with an organic black muck. The muck is now hard black shale (an oil shale) which is one of the most distinctive of all geologic formations in Kentucky. The Mississippian sandstones and siltstones are the result of a great influx of mud, silts, and sands brought in by rivers and streams from uplands many miles away and deposited as a great delta. The most common rock types in Larue County are Mississippian limestones, which were deposited 350 million years age in the bottom of a warm, shallow sea. Over the last one million years unconsolidated Quaternary sediments have been deposited along the larger streams and rivers. Geologic Formations in the County Limestones Interbedded clay shales, siltstones, and sandstones Fractured shales Interbedded limestones and shales Interbedded limestones, sandstones, and shales For more information, see the definitions of geologic terms and rock descriptions, a geologic map of the county, a summary of the geology of Kentucky, and a discussion of fossils and prehistoric life in Kentucky. Previous--Next--Back to "Groundwater Resources in Kentucky"
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